JPH09107673A - Drive circuit for power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a switching noise without changing a carrier frequency, e.g. in a PWM control operation in a power conversion apparatus which is constituted of a voltage-controlled self-arc-extinguishing semiconductor element. SOLUTION: Drive circuits 50, 60 for a self-arc-extinguishing semiconductor element are formed in such a way that an ON-OFF signal and a changeover signal, for the element, which are instructed from the outside are input and that the rise time and the fall time of a gate voltage for the self-arc- extinguishing semiconductor element are changed over by the changeover signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a voltage-controlled self-extinguishing type semiconductor device such as an insulated gate bipolar transistor (hereinafter referred to as an IGBT).

[0002]

2. Description of the Related Art FIG. 4 shows a power conversion system having six sets of switching circuits each having an IGBT as a voltage control type self-extinguishing type semiconductor device and a diode connected in anti-parallel, and having a three-phase bridge connection. It is a main circuit block diagram which shows the prior art example of an apparatus. In the main circuit configuration diagram shown in FIG.
1, the DC power is supplied to the three-phase bridge inverter 30 via the smoothing capacitor 22, and the DC power is converted to AC power by the three-phase bridge inverter 30 and supplied to the electric motor 25.
0 is formed from the IGBTs 31 to 36 and the diodes 37 to 42, and each of the IGBTs 31 to 36 is provided with a drive circuit having the same function, but in FIG.
Only the drive circuit 43 of the BT 31 is shown.

FIG. 5 is a detailed circuit diagram of the drive circuit 43 of the IGBT 31 shown in FIG. 4, in which 1 is a photocoupler, 2 is a resistor, 3 is an inverter element, 4 is an on-resistance, 5 is an on-transistor, and 6 Is an off resistance, 7 is an off transistor, 8 is an on power supply, and 9 is an off power supply. The operation of the drive circuit 43 will be described below.

On-command from the outside to the drive circuit 43
When the off signal changes from off to on, the output of the photocoupler 1 via the resistor 2 becomes low level, and the inverter element 3
Output becomes high level, the on-transistor 5 is turned on, and the on-power source 8 passes the on-resistance 4 to the IGBT.
A charging current flows through the gate-emitter capacitance of T31, and the gate-emitter voltage rises. When the gate-emitter voltage exceeds the threshold value, the IGBT 31 shifts to the ON state. Further, when the ON / OFF signal changes from ON to OFF, the output of the photocoupler 1 via the resistor 2 becomes high level, the output of the inverter element 3 becomes low level, the OFF transistor 7 becomes conductive, and the OFF transistor 7 becomes OFF. A discharge current flows from the power supply 9 to the gate-emitter capacitance of the IGBT 31 through the off-resistance 6, and the gate-emitter voltage drops. When the gate-emitter voltage becomes equal to or lower than the threshold value, the IGBT 31 shifts to the off state.

Here, the switching speed of the IGBT and the
Figure 6 shows the relationship between the on-resistance and off-resistance.
The following is a description with reference to the drawings. That is, the above
.IGBT gate-emitter voltage based on off signal
(V _GE) The waveform is from the current value (solid line in Fig. 6) to the on resistance.
Increase the resistance value of the
And the charging / discharging current described above decreases, as shown by the broken line in FIG.
The IGBT rises and falls slowly,
Rector-emitter voltage (V_CE) Waveform is also the current value (Fig. 6)
From the solid line), as shown by the broken line in FIG.
The operation of the IGBT and the turn-off operation are similar.
The waveform of the lector current (Ic) also has a relationship between a solid line and a broken line.

[0006]

According to the drive circuit of the conventional power converter described above, since only one type of on-resistance and one type of off-resistance are provided, for example, a self-powered device that constitutes a PWM-controlled power converter is used. If the switching noise generated when the arc-extinguishing semiconductor device is turned on or off causes a malfunction such as malfunction of protective equipment such as earth leakage breaker and other equipment, lower the carrier frequency of PWM control. This has been dealt with by reducing the number of times the switching noise occurs.

However, when the carrier frequency is lowered, electromagnetic noise from the electric motor, which is the load of the PWM-controlled power converter, increases, and the control performance of the power converter deteriorates. At the same time, the output current of the power converter increases. There is a problem that the current duty of the self-arc-extinguishing type semiconductor device increases due to the increase of ripples. An object of the present invention is to provide a drive circuit for a power converter that solves the above problems.

[0008]

According to the first aspect of the present invention, there are provided a plurality of sets of switching circuits each having a voltage-controlled self-arc-extinguishing type semiconductor element and a diode connected in anti-parallel, and having a bridge connection. In the power conversion device, the drive circuit of the self-arc-extinguishing semiconductor element has different turn-on time and turn-off time of the self-arc-extinguishing semiconductor element based on an on / off signal and a switching signal externally instructed. Output the gate signal to switch to the value.

In a second aspect based on the first aspect, the drive circuit is configured so that the drive circuit has a rising time and a falling time of the gate voltage of the self-arc-extinguishing type semiconductor device based on the on / off signal and the switching signal. It outputs a gate signal that switches and to different values. Further, in a third aspect based on the first aspect, the drive circuit outputs a gate signal in which the output impedance of the drive circuit is switched to a different value based on the on / off signal and the switching signal.

[0010]

1 is a main circuit configuration diagram of a power converter showing an embodiment of the present invention. I shown in FIG.
Although each of the GBTs 31 to 36 is provided with a drive circuit having the same function, the drive circuits 50 and 6 of the IGBT 31 are typically used.
Only 0 is shown, and in addition to the on / off signal externally instructed, a switching signal externally instructed is input to the drive circuits 50 and 60 in comparison with the conventional example shown in FIG. .

[0011]

【Example】

[Embodiment 1] FIG. 2 shows a first embodiment of the present invention.
FIG. 2 is a detailed circuit configuration diagram of a drive circuit 50 shown in FIG. 1. In FIG. 2, 1 and 11 are photocouplers, 2 and 12 are resistors,
3 is an inverter element, 4 and 14 are on resistors, 5 and 15
Is an on transistor, 6 and 16 are off resistors, and 7 and 1.
Reference numeral 7 is an OFF transistor, 8 is an ON power supply, 9 is an OFF power supply, and 13 is a changeover switch.

The operation of the drive circuit 50 will be described below. In the normal state, it is assumed that the output of the photocoupler 11 via the resistor 12 becomes high level by the switching signal externally instructed to the drive circuit 50, and the a contact of the changeover switch 13 is closed. In this state, when the ON / OFF signal externally commanded to the drive circuit 50 changes from OFF to ON, the output of the photocoupler 1 via the resistor 2 becomes low level,
The output of the inverter element 3 becomes a high level, the ON transistor 5 becomes conductive, the charging current flows from the ON power source 8 to the gate-emitter capacitance of the IGBT 31 through the ON resistor 4, and the gate-emitter voltage becomes high. Rises. When the gate-emitter voltage exceeds the threshold value, the IGBT
31 is turned on. Further, when the on / off signal changes from on to off, the photocoupler 1 via the resistor 2
Output becomes high level, the output of the inverter element 3 becomes low level, and the off transistor 7 becomes conductive.
A discharge current flows from the off power supply 9 to the gate-emitter capacitance of the IGBT 31 via the off resistance 6 to turn off the gate-
The emitter voltage drops. When the gate-emitter voltage becomes equal to or lower than the threshold value, the IGBT 31 shifts to the off state.

Next, when the switching signal is input to the drive circuit 50 to switch from the normal state for the purpose of reducing the switching noise, the output of the photocoupler 11 via the resistor 12 becomes low level. The b contact of the changeover switch 13 is closed. With the b contact of the changeover switch 13 closed, when an on / off signal externally instructed to the drive circuit 50 changes from off to on, the on transistor 15 becomes conductive and the on power supply 8 causes the on resistance 14 to turn on. A charging current flows through the gate-emitter capacitance of the IGBT 31 via the IGBT 31, and the gate-emitter voltage rises. When this gate-emitter voltage exceeds the threshold value, I
The GBT 31 shifts to the ON state. Further, when the on / off signal changes from on to off, the off transistor 1
7 becomes conductive, a discharge current flows from the power supply 9 for OFF through the resistance 16 for OFF to the capacitance between the gate and emitter of the IGBT 31, and the voltage at the gate-emitter drops. This gate
When the emitter voltage becomes lower than the threshold value, the IGBT 31 shifts to the off state.

In the drive circuit 50 described above, the resistance value of the ON resistor 14 is set larger than the resistance value of the ON resistor 4, and similarly, the resistance value of the OFF resistor 16 is set larger than the resistance value of the OFF resistor 6. Changeover switch 13
In the state where the b contact is closed, the rising time and the falling time of the gate voltage (V _GE ) of the IGBT 31 become gradual, and the IGBT 31 performs gradual turn-on operation and turn-off operation as shown in FIG. As a result, the switching noise can be reduced.

In FIG. 2, the same operation as in FIG. 2 can be performed even if the connection order of the on-resistance and the on-transistor and the off-resistance and the off-transistor is exchanged, and the gate voltage is the same. It is possible to individually set the rising time and the falling time of each. [Second Embodiment] FIG. 3 shows a second embodiment of the present invention.
FIG. 3 is a detailed circuit configuration diagram of a drive circuit 60 shown in FIG. 1.

In FIG. 3, reference numerals 1 and 11 denote photocouplers,
Reference numerals 2 and 12 are resistors, 3 is an inverter element, 61 and 62 are on / off resistors, 63 is an on transistor, 64 is an off transistor, 8 is an on power supply, 9 is an off power supply,
Reference numeral 65 is a changeover switch. The operation of the drive circuit 60 will be described below. In the normal state, the photocoupler 1 via the resistor 12 is switched by a switching signal externally instructed to the drive circuit 60.
It is assumed that the output of 1 becomes high level and the a contact of the changeover switch 65 is closed.

In this state, when the on / off signal externally instructed to the drive circuit 60 changes from off to on, the resistance 2
The output of the photocoupler 1 via the low level, the output of the inverter element 3 becomes the high level, the ON transistor 63 becomes conductive, and the gate of the IGBT 31 from the ON power source 8 via the ON / OFF resistor 61. A charging current flows through the emitter-capacitance, and the gate-emitter voltage rises. When this gate-emitter voltage exceeds the threshold value, I
The GBT 31 shifts to the ON state. Further, when the ON / OFF signal is turned from ON to OFF, the output of the photocoupler 1 via the resistor 2 becomes high level, the output of the inverter element 3 becomes low level, and the OFF transistor 64 becomes conductive and becomes OFF. A discharge current flows from the power supply 9 to the gate-emitter capacitance of the IGBT 31 through the on / off resistor 61, and the gate-emitter voltage drops. When the gate-emitter voltage becomes equal to or lower than the threshold value, the IGBT 31 shifts to the off state.

Next, when the switching signal is input to the drive circuit 60 to switch from the normal state for the purpose of reducing the switching noise, the output of the photocoupler 11 via the resistor 12 becomes low level. The b contact of the changeover switch 65 is closed. When the b contact of the changeover switch 65 is closed and the on / off signal externally instructed to the drive circuit 60 changes from off to on, the IGBT 31 is turned on from the on power source 8 via the on / off resistor 62.
Charging current flows through the gate-emitter capacitance of the
The voltage between the emitters increases. When the gate-emitter voltage exceeds the threshold value, the IGBT 31 shifts to the ON state. Further, when the ON / OFF signal changes from ON to OFF, the I / O signal is supplied from the OFF power supply 9 through the ON / OFF resistor 62.
A discharge current flows through the gate-emitter capacitance of the GBT 31, and the gate-emitter voltage drops. When the gate-emitter voltage becomes equal to or lower than the threshold value, the IGBT 31 shifts to the off state.

In the drive circuit 60 described above, the resistance value of the on / off resistor 62 is set larger than the resistance value of the on / off resistor 61, so that the IGBT 31 of the IGBT 31 is closed when the contact b of the changeover switch 65 is closed. The rise time and the fall time of the gate voltage (V _GE ) become gradual, and the IGBT 31 performs gradual turn-on operation and turn-off operation as shown in FIG. 6, and as a result, the switching noise can be reduced. it can.

[0020]

According to the present invention, in a power conversion device composed of a voltage control type self-extinguishing type semiconductor element or the like, in a normal operating state, a small value of ON resistance, OFF resistance, ON / OFF The drive circuit for the self-extinguishing type semiconductor element is formed by the resistance for operation, the power converter is operated, and when the above-mentioned switching noise becomes a problem in this state, the resistance for turning on and off of a larger value than in the normal state. Resistance,
By forming the drive circuit of the self-extinguishing type semiconductor device by the on / off resistance and operating the power conversion device, the switching noise can be reduced without lowering the carrier frequency of PWM control, for example. it can.

[Brief description of the drawings]

FIG. 1 is a main circuit configuration diagram of a power conversion device showing an embodiment of the present invention.

FIG. 2 is a detailed circuit configuration diagram of a drive circuit of the power converter showing the first embodiment of the present invention.

FIG. 3 is a detailed circuit configuration diagram of a drive circuit of a power converter showing a second embodiment of the present invention.

FIG. 4 is a main circuit configuration diagram of a power conversion device showing a conventional example.

5 is a detailed circuit configuration diagram of a drive circuit of the power conversion device shown in FIG.

FIG. 6 is an explanatory diagram of the operation in FIG. 5;

[Explanation of symbols]

 1,11 Photocoupler 2,12 Resistance 3 Inverter element 4,14 ON resistance 5,15,63 ON transistor 6,16 OFF resistance 7,17,64 OFF transistor 8 ON power supply 9 OFF power supply 13,65 Changeover switch 21 DC power supply 22 Smoothing capacitor 25 Electric motor 30 Three-phase bridge inverter 31-36 IGBT 37-42 Diode 43,50,60 Driving circuit 61,62 On / off resistance

Claims (3)

[Claims] 1. A power conversion device comprising a plurality of sets of switching circuits each comprising a voltage-controlled self-arc-extinguishing semiconductor element and a diode connected in anti-parallel, and connecting these in a bridge connection. The element drive circuit outputs a gate signal for switching the turn-on time and the turn-off time of the self-arc-extinguishing semiconductor element to different values based on an on / off signal and a switching signal externally instructed. And a drive circuit of the power converter. 2. The drive circuit of the power converter according to claim 1, wherein the drive circuit rises and rises a gate voltage of the self-arc-extinguishing semiconductor device based on the on / off signal and a switching signal. A drive circuit for a power conversion device, which outputs a gate signal for switching a fall time to a different value. 3. The drive circuit of the power converter according to claim 1, wherein the drive circuit switches the output impedance of the drive circuit to different values based on the on / off signal and the switching signal. A drive circuit for a power conversion device, wherein: